9124 B2B credit question.

Answered Question
Jul 1st, 2007
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Greetings,


I saw the following statement on the Cisco site about the 9124.


<quote>


Each port group consisting of 4 ports has a pool of 64 buffer credits, with a default of 16 buffer credits per port. When extended distances are required, up to 61 buffer credits can be allocated to a single port within the port group. This extensibility is available without additional licensing.


</quote>


This leads me to how many B2B credits are needed for 10 Km when using 2 GB ISL's? If I wanted to run 2 x 2 GB ISL as a port channel, I suppose they have to be in different port groups especially if I had to go for 20 or 30 Km. If I make a port an TE port, can the other ports in the port group be used? I know that 2nd Gen cards on the MDS 95xx series allow this but I don't know about the 9124.


Regards


Stephen

Correct Answer by pperazzo about 10 years 1 week ago

Hi Stephen,

yes, you can still use the other ports in the same port group even if you configure one as TE (that was a limitation of 9120 and 9140 only, first generation of products; 9124 is based on a new Switch on Chip architecture).

If you are running the links at 2Gbps, and you want to reach 20-30 km you will need from 20 to 30 buffer to buffer, having more than half left to be shared by remaining ports in the port group.


Regards,

Paolo

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inch Sun, 07/01/2007 - 17:12
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Heya Stephen,


All gen1 oversubscribed line cards (which includes the 91xx) you can only use the non-over subscribed ports as a TE or E unless you use the first port in the group and shutdown the other three ports in the group.


Cheers


Andrew


stephen2615 Sun, 07/01/2007 - 23:27
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Hi Andrew,


I was not sure about what the 9124 had as far as Gen 1 or 2 type ports. It surely gobbles up ports when you want to do some ISL'ing.


I am in two minds on what to do with these switches. I like the 9140 as you can do IVR, the 9120 is EOL'ed very soon so there is no point in getting them and then there is the 9214 which seems well priced but no IVR and this lose of ports when you ISL which is one of the main things I will be doing with the 9124.


I would really like some 9216x's but they are well over priced for what I want to do.


Thanks for the reply.


Stephen



Correct Answer
pperazzo Sat, 07/14/2007 - 10:12
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Hi Stephen,

yes, you can still use the other ports in the same port group even if you configure one as TE (that was a limitation of 9120 and 9140 only, first generation of products; 9124 is based on a new Switch on Chip architecture).

If you are running the links at 2Gbps, and you want to reach 20-30 km you will need from 20 to 30 buffer to buffer, having more than half left to be shared by remaining ports in the port group.


Regards,

Paolo

stephen2615 Sat, 07/14/2007 - 16:34
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Hi Paolo,


Thats exactly the information I needed. Considering that the 9124 is a recent offering, I hoped it might not have the issues that the first gen switches had.


Its interesting as Brocade went out of their way telling me the 9124 was still based on 1st Gen technology. As a matter of fact, they still don't even acknowledge the 2nd gen cards have the ability to use all the ports in the port group when an E port is created. What a great marketing ploy they have.


Stephen

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